The present invention generally relates to application of liquid anhydrous ammonia as a fertilizer and, more specifically, to an improved method and apparatus for application of anhydrous ammonia in combination with a covering spray of water or other suitable liquid to combine with the anhydrous ammonia, so as to prevent its escape into the atmosphere.
Farmers have used anhydrous ammonia for many years as a highly effective fertilizer for fixing nitrogen in soil, especially because it is relatively cheap compared to other forms of nitrogen fertilizers. Anhydrous ammonia used for such purposes is stored in a liquid state, but quickly evaporates into a gaseous state at atmospheric pressure. In order to reduce the escape of gaseous ammonia into the atmosphere, application devices conventionally use compaction wheels following closely behind the ammonia injection apparatus so as to close the injection trench and compact the soil so as to trap the ammonia in the ground. Such compaction wheels often work satisfactorily in relatively loose or sandy soils, but are less effective in clay soils which tend to form large, dense clumps. In such difficult to compact soils, a significant portion of the anhydrous ammonia tends to escape into the atmosphere after its injection into the soil. As a result, its effectiveness as a fertilizer is greatly diminished.
Various means have been tried in the past to improve the utility of anhydrous ammonia as a fertilizer for clay and other compacted soils. These methods have included a variety of shapes of knives, scrapers, disks and pack wheels. Unfortunately, all of such prior art methods have proven to be only partially successful at trapping anhydrous ammonia in the soil.